Add tests for ln(1)

* Verify that when creating a hard link to a symbolic link, '-L' option
  creates a hard link to the target of the symbolic link
* Verify that when creating a hard link to a symbolic link, '-P' option
  creates a hard link to the symbolic link itself
* Verify that if the target file already exists, '-f' option unlinks it so
  that link may occur
* Verify that if the target file or directory is a symbolic link, '-shf'
  option prevents following the link
* Verify that if the target file or directory is a symbolic link, '-snf'
  option prevents following the link
* Verify that '-s' option creates a symbolic link
* Verify that '-w' option produces a warning if the source of a symbolic
  link does not currently exist

Submitted by:	shivansh
Reviewed by:	asomers, ngie
MFC after:	1 month
Sponsored by:	Google, Inc (GSoC 2017)
Differential Revision:	https://reviews.freebsd.org/D11084

bin/ln/Makefile

@@ -1,6 +1,8 @@
 #	@(#)Makefile	8.2 (Berkeley) 5/31/93
 # $FreeBSD$
 
+.include <src.opts.mk>
+
 PACKAGE=runtime
 PROG=	ln
 MAN=	ln.1 symlink.7
@@ -8,4 +10,8 @@ MAN=	ln.1 symlink.7
 LINKS=	${BINDIR}/ln ${BINDIR}/link
 MLINKS=	ln.1 link.1
 
+.if ${MK_TESTS} != "no"
+SUBDIR+= 	tests
+.endif
+
 .include <bsd.prog.mk>

bin/ln/tests/Makefile

@@ -0,0 +1,5 @@
+# $FreeBSD$
+
+ATF_TESTS_SH+=  ln_test
+
+.include <bsd.test.mk>

bin/ln/tests/ln_test.sh

@@ -0,0 +1,217 @@
+#
+# Copyright 2017 Shivansh Rai
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+#
+
+set_umask()
+{
+        if ! umask 022; then
+                atf_fail "setting umask failed"
+        fi
+}
+
+atf_test_case L_flag
+L_flag_head()
+{
+        atf_set "descr" "Verify that when creating a hard link to a " \
+                        "symbolic link, '-L' option creates a hard" \
+                        "link to the target of the symbolic link"
+}
+
+L_flag_body()
+{
+        set_umask
+        atf_check touch A
+        atf_check ln -s A B
+        atf_check ln -L B C
+        stat_A=$(stat -f %i A)
+        stat_C=$(stat -f %i C)
+        atf_check_equal "$stat_A" "$stat_C"
+        atf_check -o inline:'B: symbolic link to A\n' file B
+}
+
+atf_test_case P_flag
+P_flag_head()
+{
+        atf_set "descr" "Verify that when creating a hard link to a " \
+                        "symbolic link, '-P' option creates a hard " \
+                        "link to the symbolic link itself"
+}
+
+P_flag_body()
+{
+        set_umask
+        atf_check touch A
+        atf_check ln -s A B
+        atf_check ln -P B C
+        stat_B=$(stat -f %i B)
+        stat_C=$(stat -f %i C)
+        atf_check_equal "$stat_B" "$stat_C"
+}
+
+atf_test_case f_flag
+f_flag_head()
+{
+        atf_set "descr" "Verify that if the target file already exists, " \
+                        "'-f' option unlinks it so that link may occur"
+}
+
+f_flag_body()
+{
+        set_umask
+        atf_check touch A B
+        atf_check ln -f A B
+        stat_A=$(stat -f %i A)
+        stat_B=$(stat -f %i B)
+        atf_check_equal "$stat_A" "$stat_B"
+}
+
+atf_test_case target_exists_hard
+target_exists_hard_head()
+{
+        atf_set "descr" "Verify whether creating a hard link fails if the " \
+                        "target file already exists"
+}
+
+target_exists_hard_body()
+{
+        atf_check touch A B
+        atf_check -s exit:1 -e inline:'ln: B: File exists\n' \
+                ln A B
+}
+
+atf_test_case target_exists_symbolic
+target_exists_symbolic_head()
+{
+        atf_set "descr" "Verify whether creating a symbolic link fails if " \
+                        "the target file already exists"
+}
+
+target_exists_symbolic_body()
+{
+        atf_check touch A B
+        atf_check -s exit:1 -e inline:'ln: B: File exists\n' \
+                ln -s A B
+}
+
+atf_test_case shf_flag_dir
+shf_flag_dir_head() {
+        atf_set "descr" "Verify that if the target directory is a symbolic " \
+                        "link, '-shf' option prevents following the link"
+}
+
+shf_flag_dir_body()
+{
+        atf_check mkdir -m 0777 A B
+        atf_check ln -s A C
+        atf_check ln -shf B C
+        atf_check -o inline:'C: symbolic link to B\n' file C
+}
+
+atf_test_case snf_flag_dir
+snf_flag_dir_head() {
+        atf_set "descr" "Verify that if the target directory is a symbolic " \
+                        "link, '-snf' option prevents following the link"
+}
+
+snf_flag_dir_body()
+{
+        atf_check mkdir -m 0777 A B
+        atf_check ln -s A C
+        atf_check ln -snf B C
+        atf_check -o inline:'C: symbolic link to B\n' file C
+}
+
+atf_test_case sf_flag
+sf_flag_head()
+{
+        atf_set "descr" "Verify that if the target file already exists, " \
+                        "'-sf' option unlinks it and creates a symbolic link " \
+                        "to the source file"
+}
+
+sf_flag_body()
+{
+        atf_check touch A B
+        atf_check ln -sf A B
+        atf_check -o inline:'B: symbolic link to A\n' file B
+}
+
+atf_test_case s_flag
+s_flag_head()
+{
+        atf_set "descr" "Verify that '-s' option creates a symbolic link"
+}
+
+s_flag_body()
+{
+        set_umask
+        atf_check touch A
+        atf_check ln -s A B
+        atf_check -o inline:'B: symbolic link to A\n' file B
+}
+
+atf_test_case s_flag_broken
+s_flag_broken_head()
+{
+        atf_set "descr" "Verify that if the source file does not exists, '-s' " \
+                        "option creates a broken symbolic link to the source file"
+}
+
+s_flag_broken_body()
+{
+        atf_check ln -s A B
+        atf_check -o inline:'B: broken symbolic link to A\n' file B
+}
+
+atf_test_case sw_flag
+sw_flag_head()
+{
+        atf_set "descr" "Verify that '-sw' option produces a warning if the " \
+                        "source of a symbolic link does not currently exist"
+}
+
+sw_flag_body()
+{
+        atf_check -s exit:0 -e inline:'ln: warning: A: No such file or directory\n' \
+                ln -sw A B
+        atf_check -o inline:'B: broken symbolic link to A\n' file B
+}
+
+atf_init_test_cases()
+{
+        atf_add_test_case L_flag
+        atf_add_test_case P_flag
+        atf_add_test_case f_flag
+        atf_add_test_case target_exists_hard
+        atf_add_test_case target_exists_symbolic
+        atf_add_test_case shf_flag_dir
+        atf_add_test_case snf_flag_dir
+        atf_add_test_case sf_flag
+        atf_add_test_case s_flag
+        atf_add_test_case s_flag_broken
+        atf_add_test_case sw_flag
+}

etc/mtree/BSD.tests.dist

@@ -18,6 +18,8 @@
         ..
         expr
         ..
+        ln
+        ..
         ls
         ..
         mv